Fairly frequently in the blogosphere one runs across blog posts that one really likes. Or even that one wishes to have written oneself. And perhaps a post or two that one has been planning to write oneself.
I've recently run across a post on The "three-paper" rule by Massimo at Exponential Book blog that draws together a series of observations on the purpose of graduate school training. I doubt that I could improve much on this discussion but I did have one or two small jumping off points that Massimo overlooked.
Getting back to the main point at hand, another way to put the question in the title is to ask quite simply, "What does it take to earn a Doctorate in Philosophy?"

Most people in a mentoring role understand that it is absolutely essential to communicate to undergraduates who plan post-graduate study of the realistic duration of training until the PhD is awarded. In the US, at any rate, the median time to completion for a lot of biomedical science related departments is around 6 years. This can come as a bit of a surprise to undergraduates who more typically anticipate a 4 year duration. As with the working hours, pay and many other facts-o-graduate-school-life, it is in nobody's interest for the entering graduate students to think it is a 4-year and out deal.
Doing a little research, I find that median registered time to completion for biomedical science PhDs in the early 1970s was right around 5.5 years. This number rose to a highwater mark of about 6.9 years in the late 1990s. Over the same interval of time, of course, the postdoctoral training interval was expanding dramatically. The number of PhD scientists in postdoctoral training at a given year following the PhD was rising, as was the number of postdoctoral years prior to landing a faculty appointment.
So who cares about one piddling little year in graduate school, right?
Well, of course it is part of the problem and it needs to be addressed. In fact, the NIH has been putting pressure on graduate departments to rein in their time-to-completion numbers. How, you ask? Via the pursestrings, of course. I don't have any official links handy at the moment but certainly several colleagues are reporting their understanding that if they don't try to reduce the number of 6 yr+ PhD students, that training grant funds will become increasingly difficult to procure.
Response has been mixed. I applaud those of my colleagues who agree that it is a good idea to keep graduate training under 6 years. Personally I think it should not be the median but something like the 95%ile that is under 6 years. I'm willing to accept that 4 years may be too short of an interval to shoot for as a graduate program median so for argument's sake...5 years?
Trying to land on a number, and grappling withe reasons for graduate studies extending past 6 years, brings us right back to the titular question. What is graduate training for? What are we trying to accomplish? When do we decide that a young scientist in training is worthy of being awarded the Ph.D. degree?
The defenders of the ever-expanding time-to-completion are frequently focused on the topic that drew my eye over at the Exponential Book blog.

In many disciplines, the widespread expectation is that by the time doctoral candidates are ready to take the final exam, their curriculum vitae will sport a number of publications, most of which with them as leading authors and/or in high-impact journals in their field of study.

I should point out that I trained in an environment/time when what I call the monolithic thesis approach still more or less ruled the day. It was giving way, however, to what we termed the "staple dissertation". This latter was a dawning situation whereby if a graduate student had managed to publish about three or more papers during graduate study, she would more or less add some limited introductory or transitioning remarks in between the papers, staple the whole thing together and submit it as the dissertation. The focus, clearly, was on the publication of papers over the generation of a monolithic tome of meticulous review, experimental methods and results and a whole lot more theorizin' about what it all meant.
Personally I think there is still room for both approaches or a hybrid of the two in forming a plan of attack on the dissertation and thesis defense. Different strokes and all that (RIP Gary Coleman). There is a tendency for either of these approaches, however, to be gated on experimental success.
This is where things get tricky.
Let us acknowledge right off the bat that it is easy to fail, as a scientist, due to incompetence, inability, lack of aptitude and/or effort. Sure. And in some senses we do not want to award the PhD to an individual who fails because of these traits. But as Massimo observed:

Lest we forget: this is research, which means, sometimes things simply do not work out. Experiments do not yield useful data, maybe they were not well thought out to begin with, theoretical approaches fail to yield any novel insight. I maintain, however, that there is a chance for students to grow into respectable science professionals, even working on doomed projects.

Exactly! And remember that graduate training involves (or should) supervision by a committee of faculty in addition to the primary mentor(s). They should easily be able to distinguish research which is not working out from a lack of effort. The committee should also be able to determine when the PI is making decisions about publication of data that is detrimental to the legitimate interests of the doctoral student, but this may be a big topic for another day.
And as Massimo also mentioned, the mere fact that a student has been fortunate to get "good" results and publish a few papers is no guarantee that she has received good training in how to be a scientist. Personally, I think having it too easy isn't all that great of preparation for the life of a Principal Investigator either. Again, the committee should be in position to realize that student Warshnozzle slotted into a productive vein in the lab but still has no intellectual engagement in the field to speak of, can't troubleshoot worth a lick and has learned only a limited number of technical skills.
Really, go read the original post, it is full of goodness.
The thing he missed, however, is the way that the expectation for publications, for first authorships and for "success" generally may influence scientific fraud and data faking. Again, I agree with Massimo that the point of graduate student training is not to generate experimental successes. It is more to learn how to be a scientist and in my view this does not require that one demonstrate wild success (in terms of publishable, hypothesis-testing, P less than oh-point-oh-five paper figures).
I recognize that stuff can happen. Yes, even in the course of a three-four year stint of training (after rotations). Sometimes a perfectly good scientist comes up blank. We know this because of our peers that have struggled mightily in one setting that have later gone on to regain their footing in another setting. I know of several such scientists personally. It is not just that I happen to like them and make excuses for their lack of success/productivity...it is that the record reflects that they are productive, roughly up to the standards of their subfields, in a different setting*.
And yet the meme is that "past productivity predicts future productivity". Experimental failure is personal; it is your failure as a scientist. A publication gap means that you, well, perish.
The more we insist on this within the Tribe of Science, the more we raise the stakes of poor experimental outcomes. I would argue that the less tolerant we are to failure, the more we encourage the faking of success.
__
*of course many unsuccessful individuals never get the chance to demonstrate their talents because an earlier lack of success pushes them off the career path in some way. I don't mean to imply that it is only the ones who do return to the track who are deserving.

The more we insist on this within the Tribe of Science, the more we raise the stakes of poor experimental outcomes. I would argue that the less tolerant we are to failure, the more we encourage the faking of success.

So what would the Michaelson-Morley experiment's failure have done to their careers if they had been graduate students in today's environment? (Never mind the question of whether they would have managed to get published.)

It was giving way, however, to what we termed the "staple dissertation". This latter was a dawning situation whereby if a graduate student had managed to publish about three or more papers during graduate study, she would more or less add some limited introductory or transitioning remarks in between the papers, staple the whole thing together and submit it as the dissertation.
This practice has been explicit in Swedish universities, at least in my field. I have at least two such theses on my bookshelf. There, the candidate need not even write transitions between the papers; it is sufficient to write an introductory chapter tying all of the papers together (typically there will be five or so, most of which are first author publications but some may not be). However, I am in a field where this makes sense; the pressure to fake a successful experiment is not as great because your worst case scenario involves falling back on one or more theoretical papers. Also, the risk that any experimental fakery will be detected prior to publication is relatively high. However, I agree that in most biomedical fields, where everything depends on experiments which yield positive results but are difficult to reproduce on short time scales, this kind of thinking will lead to pressure to cheat.
As for DC's example, my guess is that Michaelson and Morley could find a place to publish it today, but it wouldn't be in Nature or Science, and I'm not sure if Physical Review Letters would bite. There is a running joke in my field about people not believing experimental results until confirmed by theory, and M&M were definitely ahead of theory here. OTOH, if the theory of special relativity had been developed first and the prediction made that there should be no ether wind, M&M's confirmation of that prediction would have been interesting enough to make PRL.

"I find that median registered time to completion for biomedical science PhDs in the early 1070s was right around 5.5 years. This number rose to a highwater mark of about 6.9 years in the late 1990s."
Those are data just for the U.S., right?

One of the commenters at Experimental Book made the critical point that a manuscript is not equal to a publication. At my institute, one of the programs has a "two manuscript" rule for graduation. This is bullshit--even worse than a "three paper rule." On more than one occasion, two lame manuscripts were produced, allowing the student to graduate and leave--and then the papers never got published. The experience of being externally peer reviewed focusses the mind, and going through that process is part of a PhD education. If the reviewers ask for more experiments after the trainee leaves, then the PI is put into a difficult situation of enticing another person in the lab to do the work. So, they must waggle middle authorships as incentive or else asterisk authorships in order to get that paper finished. Far better for the trainee to stay those extra 6 months and claim full credit for their efforts. Everybody benefits.
The risks to the student of not publishing and then perishing are great. If the goal is to continue to pursue an academic track, then do whatever needs to be done to finish the work and publish it. The risks of the student making shit up in order to get published (and getting away with it) are manageable. Thesis committees, the mentor, outside reviewers, and experimental replication should be able to prevent/expose most fraud at this level.

Exactly! And remember that graduate training involves (or should) supervision by a committee of faculty in addition to the primary mentor(s). They should easily be able to distinguish research which is not working out from a lack of effort. The committee should also be able to determine when the PI is making decisions about publication of data that is detrimental to the legitimate interests of the doctoral student, but this may be a big topic for another day.
Assuming, of course, that such a committee is one that actually follows the progress of the student and is willing to give the primary mentors the smackdown if need be. When this happens, it's wonderful. (I talked about my personal experience with it here: http://mareserinitatis.livejournal.com/734199.html) On the other hand, I think that this is not as widely practiced as it should be.
Anyway, feel free to post something on this topic, as well. I'm very interested.

Far better for the trainee to stay those extra 6 months and claim full credit for their efforts. Everybody benefits.
Or better for the PI in a given situation to manage the publication timeline as best s/he can to ensure the trainee gets out on time, whatever that may be. If the mutterings that I have been hearing are correct, i.e., that the NIH is putting on the pressure then the PI/mentor-class needs to start thinking seriously about managing the timeline better. Instead of allowing graduate students to blunder along until something publishable miraculously arrives, they need to start with a departmental norm (say 5 yrs) and work backward from there including the additional-experiments-requested interval in the calculations.

Interesting blog-- I've been lurking for a few months and have made maybe 2 posts.
Do you hard scientists think maybe you should seriously restrict admissions into your PhD programs?
I say this for two reasons:
1. I think one can only develop a scientist (students make the school and not vice versa).
1a. Something like 80% of the pubs in any field are done by 20% of the faculty, implying to me that "good science" is an ability one is born with or not.
2. I see you all struggling for jobs, doing post docs for what I assume are crap wages, and then getting lucky if indeed a tenure track spot is landed. After a decade or so of study (and tons of student loans) I'm surprised at the relatively low salary most hard-science profs make.
At my school I was told a phd chemist would make around 40ish. We just hired a new abd management prof for 6 figures. An accounting prof could command 200k at a decent school.
This is all supply and demand driven. We struggle to get qualified applicants to fill an accounting spot. I imagine the applicants to position ratio for hard scientists is huge resulting in relatively crappy wages for the education and vita you guys bring to the table.
If I am mis-characterising, please let me know, but it seems like reducing admissions could be a good thing (I read somewhere that the demand for accounting profs in just California is larger than the supply of new phds this year...).

bpesta22,
Just out of curiosity: How on earth do you get the idea about the "implication" expressed in 1a)?
You "conclusion" as stated here is so utterly baseless* that it seems hardy worth pointing it out, but:
1) Professorships vary a LOT, from positions at elite institutions with lots of support (people as well as equipment) to positions at teaching oriented places, where a professor has hardly any time for research, let alone support. This by itself easily explains huge differences in publication output.
2) Even if we completely forget about the differences in support and assume that ability is everything, why on earth would that imply that this ability has been born with and not been acquired through training?
*) In the sense that you provide 0 base for it; not just that I may (or may not, that's not the point) think it wrong.

A number (I take that as at least 3) publications in high impact journals (from EB). By this criteria a PhD trained scientist is now someone who works quickly in a trendy field doing sexy research that may or, more likely, may not go anywhere. Probably the easiest way to get a PhD currently in a biological science is to 454 sequence 3 genomes.
Don't have to be an expert or know how to think about science or a problem or question. Just generate some rapid hot that a high impact journal can use to generate a ton of press. Maybe Mooney is right, scientists need to learn to be prostitutes PR people.

I wonder how much of the change in dissertation length from the 1970s to the present has to do with two other factors - the much greater percentage of women taking Ph.ds and also the shift towards more balanced family life. The reality of a six year Ph.d is that for most people, this puts many graduate students solidly into the marriage and kids years. Moreover, academia effectively forces choices on them - it can be easier to stop the grad school clock than the tenure one in practice if not in policy.
The lenghening of Ph.d times would seem to me to reflect not just changes in the practice of academia, but also in three other things. First, a generation of women who realize that if they don't have kids in grad school, they may effectively have to wait until the "amnio years" are solidly upon them, given the need for tenure. Second, men who have to do more parenting and domestic labor than before, so who also find themselves constrained by those facts. Third several functional generations of women who watched the baby boom era women who waited until late in life to have children undergo years of painful infertility.
Every woman in graduate school I knew spent a great deal of time on those issues, and for both men and women, these were deeply determining factors, at least as much as the kind of dissertation and scholarship they did, or their initial successes and failures.
Sharon

Sharon raises a really good point. That said, it's also possible for the decision tree to *look* like it functions in the way she describes, but not be such a tidy story.
For example, in my own case, the original plan was to firmly establish the career, then the family. In other words, skip high school, zoom through undergrad and grad school in a tremendous hurry, plan post-docs carefully and get a 'real job' before even thinking about having kids. Plan worked fine until getting through grad school ASAP failed. Due in part to factors related to being female, I crashed and burned badly in my first lab.
Then, much after-the-fact, when I realized I was nohow getting out of grad school FAST and I found myself pregnant... it seemed to be too risky to count on being able to have a kid later.
Now, at the time I got kicked out of my first lab, there were 12 other students in the same shoes, in about a year span at my institution. 11/12 were female (none, to the best of my memory, had kids or were thinking reproducing was imminent). Most, incidentally, were also foreign. I think when we talk about finding a good 'fit' in a lab, the *odds* of having some kind of problem are different for different demographics.
I wonder if an increasingly female grad student population means increasingly long periods of time-to-degree because of this factor. Which is not to say the kids thing doesn't have an effect as well. The combination could explain a lot.

Sorry-- ignore my comments re ability. I think that was a derail and would open a can o worms.
That said, anyone have thoughts on the over-supply of hard scientists and how it might be impacted salaries and whether restricting admissions could help, without hurting scientific output?

bpesta22
At some point you need a test that can discriminate between good scientists and not so good scientists.
The only test we have is actually seeing how people go for a few years and triaging at that point.
Which sucks for us.
The earlier you move the triage point the worse our ability to predict who wil be the productive scientists is. My undergraduate academic record wouldn't have gotten me in and I'm well above american standards for productivity at my career stage.

Well written (as usual). There is also the problem of what to do about students who've been given very high risk projects by PIs who refuse to see how high risk the projects really are. Ideally, if the PI is overly ambitious, the committee should intercede to help bring the project back to the realm of what is possible within a certain time frame. Otherwise, you have a situation in which the student may flounder because of the nature of the project (with little-to-no preliminary results to work off at the beginning) OR because of the lack of experience at the bench (trouble-shooting experiments, etc.), and the committee will not know what is contributing to the "lack of productivity" that they perceive. Personally, I am sick and tired of PIs who do this to their grad student and, even, postdoc trainees (in my experience, the PIs who do this are usually big names who don't know how to run a lab, but manage to crank out high impact papers from the 10-12 postdocs in their lab every few years to keep their reputations as "big shots" alive). Often, grad students (and even postdocs) are too naive to see how a lab really works to select against such mentors (making the careful selection of committee members even more important... although the grad students may be too naive to know what kind of committee members to seek out - i.e. they shouldn't just pick PI collaborators, but individuals who will actually have in-depth insight into the topic and experiments proposed).

As someone who has just started a PhD (in Aus) I find this discussion fascinating. There is no required number of publications to graduate here, you simply need to satisfy your supervisor(s) that you are making satsifactory progress throughout your tenure as a grad student. Granted in most fields that means you will produce publishable data but there is no required number of papers.
At the same time however, it was made explicitly clear to me when I started that I would want/be expected to publish roughly one paper for every year I spent in my PhD (with caveats for the time specific experiments would take etc.) But this was not in any way posed as my degree being dependent on it, it was much more that if I seriously wanted to pursue a career in science publishing papers is the way to do it.
As flawed a metric it is people will be looking at the number of papers you've published(/citations they've gotten/impact factor of journals etc.). While making a PhD depend on publishing X papers is definitely the wrong way to do things you do need to teach how to be a succesful scientist and publishing is papers is clearly fundamental to that.
PS. A PhD is 3-4 years here, anyone able to explain why its 5+ in the states? PhD entry requires a 3+ yrs undergrad degree and honours which is a year of pure research if that explains matters at all.

Part of the time difference between the UK and USA PhD lengths is a product of a different undergrad emphasis (breadth vs depth). I am not totally familiar with the Australian system but in the UK/Ireland the undergrad degree is so much more focused than in the USA it essentially means you start your PhD at a different point. I did my undergraduate in the UK and my PhD in Ireland during which time my supervisor/PI moved to the USA. There was some down time while we were setting up the lab so I took some classes with my US peers, 1st and 2nd year PhD students, and they were roughly equivalent to classes for final year undergrads in the UK.
It's not all due to this (how a PhD is funded also plays a role). But its big factor for sure and one that is unlikely to change.

Thanks very much for posting this. I'm a grad student and have been thinking about this a lot the last couple of weeks (in fact it was the topic of my very first blog post http://dancingintherig.blogspot.com/) because I had NOT been hearing this rule in my department. Instead, we are encouraged to explore, be productive, and get out in 6 years or fewer. However, an external review committee was surprised when us grad students weren't aware of the "2 paper" rule in our field. I continue to wonder whether my education will be worth any less because I am not held to that standard but its nice to hear that people at your level disagree with this rule too.

I always thought phd's in britain and australia are faster than in the states because they take zero coursework..they just come in and start doing experiments.

As some of the previous commenters have indicated, in these systems you do advanced work during your undergrad degree because you start your major on Day 1 of your freshman year. In some instances, you then do an additional honor's year which is some coursework plus a thesis - this is usually a make-or-break year where you see if you're really cut out for doctoral candidacy. You then enter the PhD program with an advisor already lined up and with some idea of the project you want to do. From there, it's 3-4 years of full time research.

What is the purpose of graduate education? Well, I don't have Ph.D. students, but when I advise undergrads thinking about grad school I say this: If you complete a Ph.D., and if you do it right (a big if), you will come out knowing how to ask and answer an original question in your chosen field of study. There is no guarantee that this will lead to fame or fortune, there is no guarantee that this will lead to any particular sort of job, there isn't a guarantee that anybody will give a damn about your question and the answer you came up with, and it isn't even necessarily true that this is the only way to learn that skill (there are people who acquired that skill via other paths). However, you will be capable of asking and answering original questions in your chosen field of study.
If that skill is something that you value, something that you want to acquire and try to use in whatever endeavors you take on next, and something for which you are prepared to make sacrifices and sweat blood and push yourself farther than you thought possible, then go for a Ph.D.
If that isn't something that you want, or at least you don't want it so badly that you are prepared to sweat blood while spending several years (years of youth and energy) forgoing the average income of a college graduate, then do yourself a favor and try something else.
And when I say that last part, I make it clear that I do not judge them negatively if they choose not to go to grad school. I'm a big believer in undergraduate research because there are things that cannot possibly be taught in a classroom or even an instructional lab where the "right" result is already known, things that can only be taught when neither the professor nor the student knows the answer. However, I find that a lot of people believe that the "right" outcome from undergraduate research is for the undergrad to then go to grad school. If my best undergraduate research student came to me and said that he would rather take the intellectual skills that he has acquired and do something else, I would salute his decision and write glowing letters of recommendation and wish nothing but the best for him.

In particular response to a line from Alex #27, who says "you will come out knowing how to ask and answer an original question in your chosen field of study" (emphasis mine).
In my experience, "field of study" would need to be defined extremely broadly, as in "science" or "literature" or "history". Getting a PhD (particularly one based on real training under a good mentor from a good school) is about learning to ask the right questions that have unknown answers and learning how to answer those questions. In particular, there are a host of deeply difficult issues related to finding the right analyses, the right controls, and learning how to plan, execute, check, and communicate those results. In my experience, the stuff you learn as a PhD translates very well across most scientific fields (e.g. as diverse as math-heavy theoretical physics and lab-heavy experimental biology).
I don't know how easy or hard it would be to translate skills from say, Renaissance literature to experimental biology. I just haven't seen it. But in my experience, skills learned in a PhD translate across most of the sciences.

i don't know if there are ways to quantify the ways i matured and changed as a person and as a scientist while i was a graduate student. it is about far more than the straight-up number of publications for me. i might haphazardly guess that the most important aspects were learning how to think all the way around a problem and proving my own worth to myself. the cranking out of repetitive assays day after day can be done by pretty much anyone. running them is the price of admission and the basis on which the ideas and critical thinking build.
i know plenty of phd graduates who skimmed by on the repetitive assays and publications like unthinking robots on pre-determined projects that required little mental challenge- and while they may have a greater n of publications than i do, i feel that i got far more value than that out of my own training.

My thesis hardly rocked the world. After the intro chapter, it consisted of:
1) A project that was assigned to me. It never really worked. I strived mightily for years to make it work, though, and in the end I learned a ton. I got just enough results to write a chapter showing that there might be something interesting there, but not enough for a paper. I did manage to spin off something from it in a collaboration with another student and make second author on that paper. But that paper is far less important than all of the things that I learned trying to make it work.
2) A project that I came up with 100% on my own because the things that I was asked to do just weren't working. That did make a paper, and while the paper never rocked the world (still hasn't been cited), it did prove that I can come up with my own original question and answer it. I consider that the most important paper I ever wrote. I don't care if nobody ever cites it. It's mine.
3) A project that they gave to me once they realized what I was able to do. That one I did very quickly, and learned a few interesting things. And it gets cited here and there. But what's more important to me is that I proved that I can do things that are useful.
So I don't assess my graduate education in terms of how fancy my CV looked at the end. I assess it in terms of what I learned from the projects. In terms of my impact on the field the things that I'm doing now are far more important than anything I did in grad school. But I wouldn't be able to do this if I hadn't learned what I learned in grad school.